Abstract: An exhaust pipe for an internal combustion engine has non-circular passages that extend from the engine exhaust port to the atmosphere. The performance of the engine is not impaired by the non-circular passages compared with prior pipes having circular passages of the same cross sectional areas at corresponding locations along the pipes. The non-circular cross section enables two or more passages to be located inside a single outer wall. Plates inside the outer wall divide the outer wall interior into the separate passages. Adjacent passages thus share a wall. The exhaust pipe includes headers that conduct exhaust gasses directly from the engine to the associated passages. In a modification of the invention, an exhaust pipe is tuned for performance at two different engine operating speeds by tuning a passage on one side of a shared wall differently than another passage on the other side of a shared wall.

Abstract: A tuned exhaust system for a multi-cylinder, reciprocating, internal combustion engine is disclosed. Each exhaust tube has approximately the same overall length resulting in a predetermined resonant frequency. The overall length includes the sum of the header tube length and the internal length of the collector assembly portions of the exhaust channels in the heat exchanger box. Calculating the correct length and bending the pipes to fit in the space available resulted in increased horsepower, reduced fuel consumption, cooler cylinder head temperatures, reduced noise and vibration for four-cylinder and six-cylinder aircraft engines.

Abstract: An exhaust gas recovery system for an internal combustion engine recovers the high heat energy generated by an exhaust gas clarification catalytic converter intermediately disposed in the exhaust system of the internal combustion engine as electrical energy without causing an increase in exhaust gas resistance. A stack device in a heat-driven type sound wave generating portion is provided at a one end of a resonance pipe. The resonance pipe is disposed adjacently to an exhaust gas clarification catalytic converter intermediately disposed in the exhaust system. A first end portion of the stack is heated by the heat generated by the catalytic converter, thereby providing the stack with a temperature gradient. A transducer for converting a sound wave generated by the sound wave generating portion attendant on the temperature gradient into electrical energy is provided at the other end portion of the resonance pipe.

Abstract: An engine exhaust silencer arrangement with a variable geometry, which is controlled by control elements in dependence of engine data. The increased exhaust noise occurring during engine operation under differing engine stroke modes is suppressed by the different geometry of the silencer arrangement.

Abstract: An improved fluid flow system for enhancing fluid flow through an opening. The first embodiment uses a first extension member for extending an opening through a perpendicular surface and a second extension member with a generally converging introductory section secured in a sealed overlapping relationship to the distal end of the first extension member. A second embodiment uses a pair of conduits of equal cross-section with a bulbous section therebetween with one of the conduits inserted into the bulbous section. A third embodiment with unequal cross-sections with the smaller diameter conduit inserted into the larger diameter conduit and sealed thereto for forming a continuous conduit.

Abstract: An exhaust system for an internal combustion engine having two banks of cylinders by which pulses of exhaust gas are alternately directed to a crossfire assembly. The crossfire assembly, which is located in the exhaust system, includes a gas accelerator chamber which divides each pulse of exhaust gas between two secondary exhaust outlets and causes a low pressure wave to occur in the exhaust system to enhance scavenging of a subsequent pulse of exhaust gas and thereby improve engine performance.

Abstract: An exhaust system which unexpectedly increases engine performance significantly contains multiple tracts for exhaust gases to travel within upon exiting an internal combustion engine. The multiple tracts can be made of individual tubes or contained in a single manifold device. The multiple tracts are comprised of a plurality of primary tracts which are connected in flow communication to the internal combustion engine. As exhaust gases are expelled from the engine, the gases travel down the primary tracts into several secondary exhaust tracts which branch from each of the primary tracts downstream of the engine. Both the primary and secondary tracts can be of generally any tubular cross-section. Additionally, the secondary exhaust tracts can range in virtually any number of tracts and geometric configuration and is limited only by space considerations.

Abstract: A combination recessed port of an internal combustion engine having a depth and inside diameter dimensions, and an adapter tube of a length exceeding the depth dimension of the recessed port, and an exhaust pipe having an inside diameter at least as large as the inside diameter of the recessed port and an outside diameter dimension greater than the inside diameter dimension of the recessed port provides improved engine efficiency and operation. The adapter tube is formed as an open ended cylinder providing an outer cylindrical surface having an annular lip formed medially, and a tapered annular surface at a distal end for mating with the exhaust pipe. The adapter inside diameter is smaller than the diameter of the exhaust port and is of such length as to enable exhaust flow to pass completely through the adapter prior to the next discharge.

Abstract: An exhaust system for an internal combustion engine having two banks of cylinders by which pulses of exhaust gas are alternately directed to a crossfire assembly. The crossfire assembly, which is located in the exhaust system, includes a gas accelerator chamber which divides each pulse of exhaust gas between two secondary exhaust outlets and causes a low pressure wave to occur in the exhaust system to enhance scavenging of a subsequent pulse of exhaust gas and thereby improve engine performance.

Abstract: Several embodiments of personal watercraft employing exhaust systems that incorporate not only a catalyst, but also an exhaust silencing device for silencing the sounds of the exhaust gases. The components are laid out in such a way that there will be minimum heat transfer from the exhaust gases to the engine compartment, and also so that there will be a cooling air flow across the exhaust system to further provide this result. In one embodiment, the silencing device is mounted transversely at the front of the engine, and in other embodiments it is disposed longitudinally to the rear of the engine. In all embodiments, the components are laid out to maintain good fore and aft and side to side balance.

Abstract: An exhaust gas system of a multi-cylinder internal-combustion engine has two groups of cylinders and one exhaust pipe system respectively and has a connection pipe between the exhaust pipe systems which is arranged close to the engine and which is constructed as a resonance pipe. The connection pipe can be shut off and opened up as a function of at least one operating parameter of the internal-combustion engine. By way of this connection pipe serving as the resonance pipe, resonance vibrations can be generated between the two exhaust pipe systems as a function of the ignition sequence and the rotational speed of the internal-combustion engine. Should these resonance effects cause a deterioration in the course in the torque as a function of the rotational speed, the switching flap is closed. When a positive effect is caused, the switching flap is opened up.

Abstract: The acoustical system has a sound-producing transducer mounted in the exhaust pipe of the engine, at proximity of the exhaust port and oriented toward the exhaust port, for emitting and directing a sound pulse toward the exhaust port. The sound-producing transducer is operable for bouncing a first sound pulse off the piston wall during the expansion cycle and immediately before opening the exhaust port, for creating a low pressure zone at the exhaust port and for enhancing the evacuation of exhaust gases from the combustion chamber. A second sound pulse is emitted at every compression cycle of the engine and directed at the exhaust port immediately before closing the exhaust port. The combination of the first and second sound pulses at every rotation of the engine provides an efficient scavenging and plugging of the engine for increasing the performance of the engine.

Abstract: An exhaust assembly for use with a motor vehicle having a combustion engine. The exhaust assembly includes an exhaust and a muffler having first and second gas flow routes. A control device controls the damping characteristic of the exhaust assembly by selectively dividing the gas flow by different amounts between the different gas flow routes. The control device, which may include a valve or a sliceable sleeve, is selectively operable by a user manually or electronically while the combustion engine is operating.

Abstract: An exhaust system for an internal combustion engine. A plenum chamber has two ports, one which is connected to a header tube for conducting a stream of exhaust gas and another which is connected to a ram tube adapted to collect outside air provided by movement of a vehicle in which the internal combustion engine is installed. The plenum chamber is constructed so that the outside air is caused to travel thereinside at least a substantially non-zero set-back distance before being permitted to join the stream of exhaust gas. Preferably, the exhaust system also includes one or more reverse flow controllers associated with respective cylinders of the internal combustion engine, downstream from the exhaust ports thereof.

Abstract: A variable exhaust resonance chamber valve system for internal combustion engine. The engine includes a cylinder having an exhaust port with an axial extent along the axis of the cylinder structure. An exhaust passage having a resonance port extends from the exhaust port to exhaust the engine. A resonance chamber extends from the resonance port and communicates with the exhaust passage through the resonance port. A port valve is adjustable between a second position, in which the port valve exposes the exhaust port throughout its axial extent and occludes the resonance port, and a first position, in which the port valve restricts the axial extent of the exhaust port and exposes the resonance port. A valve control module is connected to the port valve and functions to adjust the port valve between first and second positions in response to engine conditions. At low speeds and low output conditions, the valve is in its first position.

Abstract: The invention concerns an exhaust silencer arrangement with a transverse exhaust silencer in a four-chamber type of construction, in particular for very small passenger-transporting motor vehicles, with a 3-cylinder rear-mounted engine and an exhaust gas turbocharger. The silencer comprises a housing which is composed of two half shells and accommodates a catalyst module in an integrated manner. The catalyst module, which does not have its own housing, forms a silencer system partition which divides the silencer into a 3-pot main chamber and an additional chamber which is in particular a resonator chamber and communicates with the main chamber via connection ducts formed in the half-shell housing.

Abstract: An exhaust system for an internal combustion engine used in a marine propulsion system is provided with a water injection system by which water can be injected into the exhaust system. An engine control unit, which comprises a micro-processor, is used to select the rate of water injection into the exhaust system as a function of several predefined parameters. For example, engine speed and throttle position can be used by the micro-processor in the engine control unit to select a predefined rate of water flow into the exhaust system by selecting a predefined valve position, for an electronically controlled valve, that has been preselected and stored in the micro-processor.

Abstract: An exhaust gas cooling system for a vehicle includes a cooling fin system retrofit and a side exhaust pipe retrofit having an exhaust gas exit pipe having a first portion having a plurality of mixing portions which are either bends or internal mixing fins configured to mix vehicle exhaust gas, but not to restrict exhaust gas flow, a second portion fastened to the first portion and a chrome coated third portion fastened to the second portion and extending along the side of the vehicle. The cooling fin system retrofit includes an adjustable clamp and one or more cooling fins, each cooling fin having a base having a pair of upstanding arms, with one arm of the pair having a lip for engaging an arm of another cooling fin. An exhaust gas cooling system kit, a side exhaust pipe retrofit kit, a cooling fin kit are included.

Abstract: An exhaust pipe for an internal combustion engine has non-circular passages that extend from the engine exhaust port to the atmosphere. The performance of the engine is not impaired by the non-circular passages compared with prior pipes having circular passages of the same cross sectional areas at corresponding locations along the pipes. The non-circular cross section enables two or more passages to be located inside a single outer wall. Plates inside the outer wall divide the outer wall interior into the separate passages. Adjacent passages thus share a wall. The exhaust pipe includes headers that conduct exhaust gasses directly from the engine to the associated passages. In a modification of the invention, an exhaust pipe is tuned for performance at two different engine operating speeds by tuning a passage on one side of a shared wall differently than another passage on the other side of a shared wall.

Abstract: A single mode resonant cavity is adapted to absorb energy via a single excitation mode in a plurality of overlapping absorption bands having different respective resonant frequencies, thereby increasing the resonant bandwidth of the cavity. The high Q-factor cavity may form part of a microwave powered catalytic converter for exhaust gas, and has the advantage that as the cavity warms up and physically expands the coupling efficiency between the cavity and a relatively narrow waveband microwave source remains good.

Abstract: A double U shaped exhaust pipe having varying internal pipe diameters for increasing horsepower, designed within internal combustion engine vehicle racing or other rules that limit such features as overall size. A first stage portion of the exhaust pipe produces a first periodic flow of exhaust, with a vacuum pulse created where the pipe internal diameter increases upon the exhaust reaching a second stage portion. A third stage portion of the exhaust pipe produces a third stage periodic flow of exhaust upon the exhaust reaching an increased pipe internal diameter at a fourth stage portion. These periodic pulsed flows are matched to the opening of the intake and exhaust valves of the engine for a selected engine speed range. The matching of a vacuum pulse to the opening exhaust valve improves engine performance by drawing exhaust gases from the engine.

Abstract: An exhaust gas temperature control system for a two-stroke engine, the exhaust gas temperature control system including an electronically controlled water injection system. The electronically controlled water injection system includes a water supply conduit section for supplying water to a solenoid valve, and a spraying conduit section for injecting water into an exhaust pipe to thereby control exhaust gas temperature, and hence sonic wave speed within the exhaust pipe. A through-filter is provided as a splitting junction to provide filtered water to the electronically controlled water injection system and unfiltered water to the engine for cooling. A smoothing device in the form of an elastomer hose made of low durometer material or a pressurized bladder is included within the spraying conduit section for maintaining smooth water pressure within the water injected into the exhaust pipe.

Abstract: The present invention provides, with reference to the figure, a noise attenuator for an induction system or an exhaust system comprising a housing (10) having a gas inlet (13), a gas outlet (11) and a first gas flow passage (12) inside the housing connecting the gas inlet (13) to the gas outlet (11). A quarter wave resonator tube (14; 16; 23; 29) is provided inside the housing (10) which opens on to the first gas flow passage. The noise attenuator is an integer which can be installed as a single integrated unit in the induction system or the exhaust system. A Helmholtz resonator (21; 27) is provided inside the housing (10) which opens on to the first gas flow passage (12).

Abstract: An exhaust system tuned during low RPM operation while the exhaust chamber retains its preset tuning for optimal high RPM operation. An exhaust controller according to an embodiment of the present invention receives an RPM signal from the engine and processes the signal to activate a solenoid which controls a valve that injects coolant water into the exhaust chamber. The injection of the water into the exhaust chamber has the effect of cooling the exhaust gases, thereby increasing the density of the exhaust charge in the chamber and slowing the exhaust pulse wave, thereby optimizing performance at relatively lower RPM levels.

Abstract: In an exhaust expansion chamber or tuned pipe of a two-cycle engine in a watercraft, variable amounts of water are injected, thus cooling the temperature within the expansion chamber and matching the sonic wave speed with that of the correct rpm of the motor. Thus, by regulating the temperature of the exhaust gases in the tuned pipe with water, the efficiency of the two-cycle engine at varying revolutions per minute, is improved.

Abstract: A muffler assembly, for an exhaust system of an internal combustion engine has an exhaust gas inlet tube projected into the muffler to feed the muffler with the exhaust gas of the engine. First and second flow passages are defined through which the exhaust gas from the muffler flows independently before discharged to the open air. The controller has a pneumatic actuator that has a piston rod and a work chamber. The piston rod is adapted to reciprocate linearly in accordance with the magnitude of pressure developed in the work chamber. The pressure of the exhaust gas of the engine is fed to the work chamber of the pneumatic actuator. The actuator controls a valve assembly which includes a valve plate and a pivot shaft through which the valve plate is pivotally installed in the second flow passage of the first means.

Abstract: An exhaust system of an internal combustion engine has an exhaust gas inlet tube extending from the engine. A muffler is connected at its inlet side to the exhaust gas inlet tube. The muffler includes first and second exhaust gas flowing passages. First and second exhaust gas outlet tubes are respectively connected to the first and second exhaust gas flowing passages and extend from the muffler independently. A flow controller steplessly varies the flow passage area of the second exhaust gas outlet tube in accordance with the pressure of the exhaust gas discharged from the engine. The flow controller continuously increases the flow passage area with increase of the magnitude of the exhaust gas pressure.

Abstract: An adjustable-length exhaust system for use with two-cycle motors is disclosed. An insert section of pipe is interposed between a header pipe and a conventional tail pipe so that, when it is rotated, the overall length of the exhaust system is adjusted. The insert section is held in place between the tail pipe and a header extension pipe by a compressive force exerted by one or more springs attached between the header and the tail pipe. The insert features, on an end that slips over the header extension section, a series of graduated notches which mate with a protrusion, or "stop", formed on the mating end of a header extension section. This notch and stop combination determines the distance by which the insert section will be permitted to slip over the header extension section, and correspondingly, the overall length of the exhaust system.

Abstract: An exhaust gas-purging system for an internal combustion engine includes a catalyst arranged in an exhaust passage of the engine, for purifying exhaust gases emitted from the engine. The system detects an engine operating condition and a catalyst temperature parameter indicative of the temperature of the catalyst. The supply of secondary air to the exhaust passage and the flow path cross-sectional area of the exhaust passage are controlled based on at least one of the operating condition of the engine and the catalyst temperature parameter.

Abstract: An improved exhaust emission control device is disposed in a motor bicycle of the type in which a muffler body, containing a catalyst for exhaust emission control, is connected to an exhaust pipe extending from the exhaust port of the associated engine, and the exhaust pipe is inserted into the muffler body through the front section thereof and extends through the inner space of the muffler body to the rear section thereof. The exhaust pipe is turned back in U-shape at the rear section to the front section of the inner space of the muffler body and the catalyst, supported by a partition wall which is disposed in the muffler body, is positioned in the vicinity of the opening of the exhaust pipe.

Abstract: An intake silencer of the variable type is for reducing noise generated coming from the difference between the inner pressure and the outer pressure of a combustion chamber when an intake valve being opened or closed. The present invention for reducing noise comprises a signal processing part, a signal comparing part and a valve driving part. In the signal processing part, a RPM sensor modulates a waveform obtained by detecting the revolution number of the engine and a F/V converter changes it thereafter emitting a signal to the signal comparing part. In the signal comparing part, a plurality of comparators emit the opened and closed signal to a valve driver by comparing a output signal emitted from the signal processing part with a basic signal. In the valve driving part, when the corresponding valve driver turns on or off by virtue of the signal emitted from the corresponding comparator, a corresponding actuator opens or closes the corresponding valve dividing the inside of the side branch.

Abstract: A vehicle internal combustion engine exhaust system featuring two different exhaust routes to which the exhaust gas is directed selectively by an on-off device; the system also comprising a device for comparing parameters, consisting in engine speed, the opening angle of the throttle, and the vacuum inside the intake manifold and/or engine load, with respective predetermined values, for opening the on-off device upon the above parameters reaching the aforementioned predetermined values, and so selectively enabling the exhaust gas to flow along both the exhaust routes.

Abstract: A dynamically variable exhaust system provides for maximum efficiency of an internal combustion engine (30) by including an exhaust control device (35) which is operated by a control mechanism (33) and managed by a control unit (32). The length and cross-sectional area of the exhaust header section (36) can be varied by transversely displacing the effective exhaust passage within control device (35) while maintaining a streamlined profile of the effective passage throughout a predetermined range of displacement. The control unit (32) can be influenced by numerous operational inputs including control device position potentiometer (40), engine speed input (41), engine load input (42), vehicle braking sensor (43), exhaust emission and temperature sensor (44), and engine management system input (45).

Abstract: The specification related to an intake/exhaust air pressure balancer connected to an intake apparatus and/or an exhaust apparatus of an internal combustion engine and a method of reducing the intake/exhaust air pressure resistance. The intake/exhaust air pressure balancer in this invention is essentially consisted of a storage tank and a bypass pipe. Minimization of an intake air pressure resistance can be achieved by temporarily storing an intaken air reversely flowed at the end of an intake stroke followed by reintake of the air into a cylinder during the next intake stroke, while minimization of an exhaust gas pressure resistance can be expected by temporarily storing a rapidly expanding exhausted gas discharged during an exhaust stroke followed by redischarge through an exhaust equipment under a reduced exhaust gas pressure.

Abstract: A fuel control apparatus of an engine comprises fuel control means for controlling fuel supply means in such a manner that an amount of fuel supplied to the engine corresponds to an intake pressure on the basis of a signal outputted from intake pressure detecting means for detecting the intake pressure of an intake passageway, exhaust resistance changing means for changing an exhaust resistance of an exhaust passageway correspondingly to the operating condition of the engine, and correction means for correcting a supply amount of the fuel to be controlled by the fuel control means when the exhaust resistance of the exhaust passageway is changed by the exhaust resistance changing means.

Abstract: A valve having a housing including an inlet, an outlet, an internal passage connecting the inlet and the outlet, a pressure responsive member movably supported by the housing for opening and closing the internal passage, and a spring located between the member and the inlet for biasing the member away from the inlet.

Abstract: An exhaust silencing system for a two-cycle ported engine including an expansion chamber that communicates with the cylinder through a communication port that is opened before the exhaust port of the engine is opened so as to permit the exhaust gases to expand and reduce the noise of the engine. The communication port is either fully opened before the exhaust port is initially opened so as to achieve maximum silencing and/or is fully closed before the exhaust port is fully closed so as to avoid loss of effective compression pressure.

Abstract: The invention provides a marine propulsion device comprising a powerhead including an exhaust gas discharge port, a gearcase rotatably supporting a propeller shaft connected to the powerhead and including an exhaust gas discharge, and a lower unit including an upper portion supporting the powerhead and a lower portion connected to the gearcase, with the lower unit comprising an inner exhaust housing having a generally vertical wall, an open top in communication with the powerhead exhaust gas discharge port, a bottom having therein a first exhaust gas outlet and a second exhaust gas outlet at the top portion of the wall, and an outer exhaust housing also having a generally vertical wall in surrounding relation to the inner exhaust gas housing and defining a vertically extending generally annular space between the inner and outer exhaust gas housings, the space communicating with the second exhaust gas outlet.

Abstract: There is provided a method for controlling an exhaust system of a vehicle including a controller for controlling an open-close operation of an on-off valve which is provided at an intermediate portion of one of a pair of exhaust pipes arranged in parallel and communicating with an exhaust port of an engine depending upon running condition of the vehicle. The control method includes three control patterns different from each other, i.e., a first control pattern during an accelerated running condition of the vehicle, a second control pattern during a constant-speed running of the vehicle, and a third control pattern during a decelerated running condition of the vehicle.

Abstract: The invention relates to a method for regenerating a soot filter of a Diesel combustion engine. For the burning of soot deposited on the filter two coupled Helmholtz resonators are provided with the exhaust gases being introduced into the resonance pipes at their center portion. The timed ignition of the burners generates pressure waves in the system which may oscillate. When the top of a pressure wave is reached in one of the resonance housings, the temperature rises due to the adiabatic compression process such that the soot is ignited in the down-stream filter. Thereby the filter is regenerated due to the burning of soot. The burners are ignited in phase opposition so that the pressure waves generated by the burners are eliminated by interference at the location of the opening of the exhaust gas line into the resonance pipes. An increase of the counter pressure in the exhaust gas line due to negative feedback of the pressure waves is thereby prevented.

Abstract: An expansion tube exhaust system for an internal combustion engine, preferably a four-cycle engine, with a short diverging section connected to a much longer converging section, that absorbs the negative pressure back to the engine. The purpose of this invention is to lessen the back pressure going back to the engine.

Abstract: An in-line, two-cycle, crankcase compression, internal combustion engine having a plurality of scavenge ports and an exhaust port for each cylinder in which an exhaust control valve is positioned. To permit a compact assembly, the ports are rotated about the cylinder bore axis in a transverse plane so that the exhaust ports extend at an acute angle to a common plane containing the cylinder bore axes and the control shafts for the exhaust control valves extends perpendicularly to this plane. A wide variety of actuators are disclosed for operating the exhaust control valves simultaneously including flexible transmitters and a linkage system.

Abstract: An exhaust control valve arrangement for an in-line, two-cycle, crankcase compression engine which permits the porting arrangement to be rotated relative to the cylinder bore axis to achieve a compact configuration and wherein all of the exhaust control valves are operated by a single shaft assembly that extends parallel to a plane containing the cylinder bore axes. As a result of this orientation, the exhaust control valves provide an asymmetric exhaust port opening under at least some operative positions of the valves when the valves are in a flow obstructing position. A number of embodiments are disclosed which configure the exhaust control valves so that the port is symmetric in at least some operative obstructing positions of the valves. Also, several embodiments using curved valve configurations are disclosed.

Abstract: In a spark ignition or compression ignition four cycle internal combustion engine, an exhaust expansion chamber is sized to produce a reflected exhaust pressure wave timed to an auxiliary reopening of the exhaust valve after the intake valve has effectively closed. The reflected exhaust pressure wave causes the re-entry into the cylinder of a quantity of intake charge (which has previously been drawn into the expansion chamber) subsequent to the effective filling of the cylinder through the intake valve, the result being a boost in cylinder charge and pressure on the compression stroke of the piston. At engine design speed, the power output of the engine is substantially improved over the power output without the boost in cylinder charge and in compression stroke pressure. The particular exhaust expansion chambers and valve re-opening timing is adaptable to single and multiple cylinder four cycle engines.

Abstract: Active acoustic attenuation apparatus is provided for cancellation of noise from an exhaust pipe (12). A chamber (50) has an input (70) receiving exhaust from the exhaust pipe and directing the exhaust along a flowpath (76) to a chamber output (74). Speakers (88, 90) are transversely spaced and offset from the flowpath and introduce sound into the chamber at a space (56) having a transverse area at least as large as each speaker, to minimize acoustic loading of the speakers and to protect the speakers from the heat of hot exhaust for automotive applications, including electronic mufflers.

Abstract: An engine exhaust apparatus in which an exhaust passageway of the engine is provided with a plurality of sound deadening passsages. One common exhaust passageway from the engine is branched into first and second exhaust passageways. Each of the first and second exhaust passageways has a silencer or muffler including first and second exhaust outlet tubes with a shift valve mounted in one of these exhaust outlet tubes. A control unit controls the shift valves to close both when engine speed is in a low region, to open one of them when engine speed is in a medium region and to open both when engine speed is in a high region.

Abstract: An exhaust relief system for an outboard motor includes an exhaust chamber into which exhaust is discharged from the engine. A first passage in communication with the exhaust chamber provides contraction of the exhaust as the exhaust passes rearwardly, from which the exhaust is discharged into an expansion chamber which substantially surrounds the exhaust chamber. From the expansion chamber, the exhaust is routed through and contracted into a second passage in communication with the expansion chamber, after which it is discharged to atmosphere. The tortuous path provided by the exhaust relief system of the invention, along with the repeated expansion and contraction of the exhaust as it flows to atmosphere, provides a muffling effect at idle operation.

Abstract: An engine controller is linked to and controls simultaneously both an exhaust control valve and an on-off valves or changeover valves or a reflector in the exhaust pipe to improve engine performance. The controller positions the exhaust control valve and on-off valves or changeover valves, or reflector based upon detected engine speed and throttle position.

Abstract: The device has an entrance and an exit with two low-restriction venturi sections placed in parallel between the entrance and exit. The entering gas flow is separated into two parts, one to pass through one venturi section and the other to pass through the other venturi section. The two parts reunite as they leave the exit. The venturi sections are substantially identical and each contains at least one venturi. The two sections are axially offset from each other by a distance that is equal to one-quarter of the wavelength of the frequency of a principal noise component so that that particular noise frequency is phase shifted 180 degrees by one venturi section relative to the other with resulting cancellation and significant noise attenuation. Usage in an air induction system of an internal combustion engine for attenuating noise from the engine is illustrated. The device is capable of functioning irrespective of the direction of noise in relation to the direction of gas flow.

Abstract: Disclosed is an engine-control apparatus in which an exhaust passageway of the engine is provided with plural sound deadening passages. A portion of the plural sound deadening passages is designed to be opened or closed by a shift valve on the basis of a predetermined switching characteristic, and the pressure of the exhaust gases is changed upon the switching of the shift valve. In order to prevent torque shock to the driven wheels which may occur attendant upon operation of the shift valve to open or close or in order to reduce probability that torque shock would occur, there is provided a torque regulating apparatus which permits an adjustment of torque generator by the engine, of a transmission efficiency of power to the driven wheel, or of a switching speed at which the shift valve is switched to open or close, or a change in the switching characteristic.